The present invention relates to a zigzag running warning system for automotive vehicles which detects zigzag running of a vehicle to give a warning thereof.
During the running of a vehicle, if the side wind, for example, blows against the vehicle, the vehicle is drifted by the pressure of the wind and the driver tries to return the vehicle to the original running condition. Then, since the wind is not blowing at a constant velocity, the vehicle runs in a zigzag direction. Also, it is considered that if the driver becomes drowsy, the vehicle is caused to run in a zigzag direction. On the other hand, it is believed that during the running of a vehicle the magnitude of the terrestrial magnetism will not vary considerably and its direction also remains the same over a short distance of travel.